is a process of finishing
in aluminium metals where the appearance of the metal is changed? The appearance
must consist of stability and durability. The process works as an electrical
current from an anode find its way to the cathode. The metal item being
anodised becomes the anode part of the circuit where as the cathodes are in the
anodising tank. The electrical current forces the release of the anode which collides
with aluminium to form aluminium oxide. The colouring methods consist of: electro
colouring, combination colouring and interference colouring.
Annealing the exact opposite of hardening, it relieves
internal stresses, softens them and makes it more ductile. It is the process
where a metal is heated to very high temperature; it would be held there for a
period of time usually between hours and days and allowed to cool. For this process
to go perfectly, the process should be slow down in steels and other ferrous
metals. Condition in the furnace is controlled firmly to assure the expected
changes are going to take place.
This is the process of hardening the surface of metal
objects while the deeper metal underneath stays soft, this will form a thin
layer of harder metal called the case. For other metals like iron and steel
that have low carbon content the process would involve infusing additional
carbon into the surface layer. Generally case hardening would be done after it
has been formed into its final shape, carbon and alloy steels are suitable for
After the metal part has been soaked, the last step us to
cool. This process may force the structure to stay the same, revert to its
original form or even change from one chemical composition to another. These
changes are all predictable and for this reason metals can now be made to suit
certain structure to increase the level of their, hardness, strength and
When a piece of metal is heated to the temperature in which
a change in structure takes place, it has to stay at that particular
temperature until the entire part has been evenly heated. The more mass it has,
the longer it will take for t to be completely soaked, this is known as
The first step in a heat-treatment process would be heating.
The steal is heated to its final temperature. This helps in keeping a uniform
temperature in the part being heated. This reduces cracking and distortion.
Heat treatment could be any one of a variety of controlled
heating operations used to change the physical properties of a metal; there are
five different types of heating processes. These would be case hardening,
normalizing, hardening and tempering. Even though they all differentiate in
results, they all share three simple steps: heating, soaking and cooling.